Unexpected acceleration on diagonal movement

[jbensmann]

When moving the mouse pointer diagonally, e.g. with speed 1 to the right and 1 upwards, the total speed is not sqrt(2) as expected, but somewhat higher, so that the speed to the right is actually also higher than 1. At least this is the case for relatively slow speeds.

The cause is that mouseless is producing the same events as a physical mouse, and the speed of the pointer usually is not linear to the speed of a mouse, one can see in this diagram how they are related (the different curves show different settings):
https://wayland.freedesktop.org/libinput/doc/latest/pointer-acceleration.html#ptraccel-linear

It is generally possible to make this relation linear by configuration, but unclear whether it can be done independently of the display server (e.g. Xorg or Wayland), which would be preferable.